Go onto uni websites and look at the grades they require to go into medicine and the subjects. Without at least 2 sciences at A level you will have very little chance of getting into any uni. Also realise that for every med place at Uni there are 10 students fighting to get that seat, many have perfect A or A* grades in 2 sciences and maths. Why on earth would a Uni want to give you a place when you will only have 1 science, sorry you are just not being realistic.
The only way for you to proceed is to take a year out and resit your science GCSE. You need to get them at least to a 7 to be able to go onto A Levels or you will struggle so much. Then take Biology and Chemistry at A Level and study hard to pass them - they are very difficult. Once you can get A/A* in A Level than you can apply to uni. Otherwise listen to all the crap you like from others who have NOT got into Medicine the way they tell you. You seem very set on your way is the only way and you cant convince anyone but yourself of that.
BTW you are also wrong about remarks for GCSE, then are often done in 3 weeks!! You school calls for your papers, a teacher will look through them for any missing/wrong calculations and if they can find enough points then they can call for an appeal which will cost depending on exam board.